Air Handling Units (AHUs) are one of several components in cooling and heating systems. They are an important component as the AHU houses a number of components used in the system to provide forced air for climate control in a particular structure. AHU components typically include motors, heating/cooling coils, and blowers as well as the required interface connections to effect such climate control.
The AHU is an enclosed interconnected framed panel structure. The framed panel structures have insulated panels that are supported between framing members, also referred to as raceways, to define interconnected rectangular compartments. AHUs are typically large and bulky, the amount of floor space required to accommodate the AHU being commonly referred to as a “footprint.” Due to the layout of a particular structure, the AHU may be located in any number of locations, including rooftop installations.
While the AHU construction may be considered bulky, typically its size is dictated by the component configuration selected and performance requirements associated with those components for efficient operation. In fact, an interior compartment containing a blower assembly and the associated driving means, typically a motor and drive belt arrangement, leaves little remaining space for installation or maintenance after subtracting the volume already occupied by insulated panels, support structure, wiring and other components. Despite such limited space, it is critical that the blower assembly and the driving means be properly aligned, and in the case of a belt drive, that a sufficient, but not excessive, amount of belt tension be provided. Failure to provide proper alignment and belt tension may both decrease the operating efficiency of the motor and blower assembly and cause premature failure of the belt, bearings or associated components, and may cause nuisance tripping of the motor overload switch due to overloading the motor. Additionally, movement, or slippage, between the belt and the driving means may generate noise due to inadequate belt tension.
In response to this concern, Japanese Publication No. 02225850A is directed to a pair of adjustable pneumatic dampers interposed between a blower and a motor for maintaining both a parallel alignment between the rotary shafts of the blower and the motor and constant belt tension. In response to changes in belt tension during the operation of the motor and blower, valves within the dampers regulate the amount of force exerted by one damper with respect to the other to provide the parallel alignment between the rotary shafts of the blower and the motor. However, the requirement for pneumatic dampers, a pneumatic source for adjusting the pneumatic dampers, valves, and the control system necessary to monitor and maintain both alignment and belt tension adds significant costs to the AHU construction.
What is needed is an air handling unit construction provided with a motor belt tensioning construction that is both easily and controllably adjustable in tight quarters having a minimum number of components to minimize costs associated with fabrication and installation.